1. Field of the Invention
The present invention relates to a device for performing compression and expansion of image data.
2. Description of the Background Art
Recently have been produced digital cameras capable of picking up moving images. Such a digital camera needs a circuit for converting image data outputted from a sensor such as a CCD into compressed data of moving image, and also needs a circuit for expanding the compressed data of moving image stored in a memory so as to be displayed on an LCD. Further, most of digital cameras each comprise a dedicated chip for compression and expansion, besides a chip for main processing to perform general control thereof. With such a construction, chips have general versatility.
Patent Document 1, Japanese Patent Application Laid Open Gazette No. 2003-150141, discloses a technique to increase the display speed for moving image data. Patent Document 2, Japanese Patent Application Laid Open Gazette No. 10-78769, discloses a technique to increase the speed for transmitting expanded image data on a bus and increase the efficiency of use of memories.
Most of sensors such as CCDs output RGB image data. Therefore, most of main processing chips each comprise an input interface for RGB image data outputted from the sensor. Further, most of the main processing chips each comprise an interface for outputting YUV image data to a display device such as an LCD. Alternatively, in some products, the main processing chip comprises an input interface for YUV image data.
Providing a variety of input interfaces to each chip for compression and expansion, however, even in order to adapt to various types of main processing chips, causes an increase in circuit scale and manufacturing cost, resulting in lower efficiency. Further, providing a variety of input interfaces to each main processing chip also results in lower efficiency.
Integrating a block for performing compression and expansion into the main processing chip, instead of providing a chip for compression and expansion independently, is another possible method to solve the above problem on interface, but this method can not maintain the general versatility of main processing chip and causes an increase in cost per main processing chip. Further, Patent Documents 1 and 2 disclose no method to solve the above problem, such as providing a circuit using a general-purpose chip.